Customers want quality improvement of interior as well as performance improvement of a vehicle. Vehicle interior materials play an important role in quality improvement of interior. In particular, high gloss of interior materials can embody fancier interior, and can increase customer's satisfaction.
In the case of acrylonitrile butadiene styrene (ABS), which is a representative interior material widely used today, gloss is reduced due to rough surface generated during injection molding. In order to solve the gloss reduction problem of the ABS, a method of double coating (2 coat) of a polyurethane-based high gloss coating composition on the ABS material is conducting.
Further, in Korean Patent Laid-Open Publication No. 2010-0106714 (Patent Document 1), a method for preparing a high gloss panel by forming an ABS sheet layer on one side of a decoration film, coating a hard coating composition comprising a fluorinated acrylate copolymer on top of the ABS sheet, and the hardening thereof is disclosed. The fluorinated acrylate copolymer used in the Patent Document 1 is a copolymer wherein a fluorinated compound is introduced to a backbone of an acrylate resin having three or more functional groups as a substituent.
As shown above, in the conventional method, an additional coating of a urethane resin or a fluorinated resin on parts where the ABS material is used was applied to increase gloss.
As a general method for coating the fluorinated resin, there is a powder coating method and a solution coating method.
In the powder coating method, fluorinated resin powder is sprayed to a subject to be coated, and sintered by high temperature heating to form a coating film. However, because the melting point of a general polymer to be coated such as ABS is lower than the heating temperature, the powder coating method is mainly used for coating metal rather than the polymer.
The solution coating is a method of forming a coated film by dissolving a fluorinated resin in a solvent and coating thereof on a subject to be coated, and it has an advantage that the process is conducted at a low temperature condition. However, there is a limit to directly apply the solution coating method to the general polymer to be coated such as ABS because the solvent to dissolve the resin has strong polarity. Thus, in order to prevent the ABS to be coated from dissolving by the polar solvent, a hydrophilic intermediate layer, which is not dissolved by the polar solvent, is needed. Namely, forming a hydrophilic thin film on the hydrophobic surface of the ABS to be coated is needed, and UV ozonization is mainly used. However, the UV ozonization forms scratches on the ABS substrate surface, and therefore, it makes surface roughness worse. Accordingly, it is not suitable for high gloss coating.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.